Simple transform distorting loop cuts
So lets say i have this object that i want to make a straight loop cut in:



However, as you can see, this loop cut isn't straight, since the object isn't symmetrical.

Option 1: Straighten out your loop cuts

If you want your loop cuts to be flat along, say, the Y axis, then after selecting your loop cut, you can just do S > Y > 0 to make them flat in that axis.



Option 2: Bisect tool

What if your object isn't aligned along the axis? What do you do then? Or what if you are just too lazy for a two step process?

Well then you can use the bisect tool.

Select your object, and using the search bar (or some other method), select bisect. Then, you can just drag where you want your cut to be, and it will make a loop cut along that line!



The one issue with this is that it is hard to get a perfectly aligned bisection because your cursor is imprecise, but option 1 can help with that.